It is debatable, however many football people think left tackle is a difficult position to play. Go figure.

I think a lot of defensive ends thinks otherwise.

What's your opinion?

Well, umm, tackle and defensive end are quite inextricably linked. More then any other position comparison, tackle vs end is an individual battle for almost the entire game. (Corners have safties, pass rush, etc.) Most positions have complicating factors, but apart from the David Carrs or Peyton Mannings of the world at Qb, the guy across from you dictates how hard your day is going to be. Since Mario has basically been the pass rush this year (and a pretty strong candidate for our best player, defensive or otherwise), while D'Brick has been abused on a number of ocassions, I think that agument has a pretty decisive edge in #90's favour.
In regards to what is more important, a great tackle or great defensive end, I would say it depends on your team and division. We have Peyton Manning and a history of two-minute drill nightmares working against us. I would say for us, Mario at his potential best is a proposition that is hard to pass up for anyone else in the 06 draft.